1. A Class Project for the Gwinnett Woodworkers Association Louis and Ricky Alexander

2.  Lumber under 22% moisture content (MC) has no risk of developing fungal stain, decay, rot, or mold  Dry Lumber weighs over 50% less than wet lumber  Dry lumber is over twice as strong and twice as stiff as wet lumber  Nails and screws in dry lumber have higher holding power  Dry lumber is easier to glue  Dry lumber machines better than wet lumber (unless dried under 5% MC)  Dry wood finishes easier  Dry lumber will shrink and swell in-use less than wet lumber that dries in use  Woods to Woodshop, Woodmizer.com

3.  Hand tools have a better feel and are easier to work with air dried lumber  Not as brittle or dusty as kiln dried wood  Preferred in rooms that are not conditioned with modern HVAC systems (garages, laundry rooms, shops that are not heated or cooled)  Very low cost especially if you have your own tools to finish milling the lumber (around 0.30 BF to mill – even less if you own a sawmill)

4.  Seal the ends of the logs as soon as they are cut  At least 8 inches clearance at the bottom of the stack (12 inches is better)  Dry Stickers / same species between each row  Flat foundation to maximize straightness  Particularly above 40% MC, ensure good gentle air flow with some relax time  Protect from rain and insects

5. http://www.finewoodworking.com/how-to/video/how-to- dry-lumber.aspx Tin roof and Shade Cloth houses for air drying

6.  The lumber is subject to attack from insects especially long term  More likely to stain from mold and mildew  Is more likely to crack if air flow is minimal or is exposed to direct sun  Variability and extremes of weather causes approximately 10% greater loss  In typical air humidity here in the south with an average of 65%, 12% MC is approximately the limit of dryness expected

7.  Temperatures above 140 o F will typically kill all the fungi and insects present  A carefully controlled elevated temperature and environment will significantly speed up the drying process with less loss to damage  Quality is improved = increased value  Most conditioned air spaces average 38% RH which means the MC should be ideally be 7- 8% to prevent excessive movement and cracking. Not possible with air drying

8. Oak shrinks 1% for every 3% change in MC Example: A 2 ½ inch wide bard loses 3% MC causing a change of 1% or 0.025 inches. Seems like a small amount but consider the maximum gap allowed for adhesion between glue lines is 0.006 inches. Plus say this is a 30 foot wide section of flooring, you would be losing 4 inches over the span – can you say cracks everywhere. Woods to Woodshop, Woodmizer.com

9. The primary choice for industry Good option for Small Shops  Gas fired or electric ◦ Offers complete control of the drying process ◦ Very fast – mill to market in approximately 3 weeks ◦ Can be sized to fit about any size operation ◦ Very expensive to build and run ◦ Produces excellent quality and color consistently  Dehumidifier Kiln ◦ Not dependent on weather ◦ Relatively low cost to build and operate as long as the loads are small ◦ Higher costs to run relative to Solar ◦ Easier to make a mistake in over-drying (case hardening)

11. Vacuum Drying – High Capacity – Super High Startup Cost

12.  Different woods have optimum drying schedules to prevent damage – not even close to optimal in the attic extremes  Want simple? – Just use the Hailwood- Horrobin equation to determine how long at what temperature to dry your wood

13.  Build a Solar Kiln as close to what is “proven” to be effective based on past experiences from the experts (Virginia Tech and others)  Record careful MC, temperature, and RH, and vent position measurements to get a feel for the performance  Cut several “test” pieces to weigh during the process – especially when the meter isn’t effective at high MC (>40%)  Use Bob Brokaw’s wood first in case I mess up

15.  The size of the collector keeps the kiln from overheating (1sq ft of collector per 10 BF of 1 inch lumber capacity)  Should dry a load in approximately 1 month  Slope of the roof should be approximately the latitude of the location (34 for Lilburn) plus up to 10 degrees if using during the winter  Overnight “relax” helps the kiln to be more forgiving to temperature fluctuations  Black interior will help to absorb the heat from the sunlight